FIG. 1 shows a perspective view of a section of a height adjustable seat part 1 of a vehicle seat according to the prior art comprising the seat part 1 and a backrest (not shown) connected to the seat part 1. The seat part 1 is arranged on a vehicle floor of a vehicle (not shown) longitudinally adjustable via a guide rail arrangement 7. The seat part 1 comprises a first side part 21 and a second side part (not shown) forming a seat frame, wherein a rear cross tube 4 and a front cross tube (not shown) extend there between. The rear cross tube 4 is mounted pivotably to the side parts 21 and carries a first rocker 3 and a second rocker (not shown) which form a rear rocker pair. An arc weld 40 axially secures an end 41 of the cross tube 4.
A front rocker pair is formed by a third and fourth rocker which form together with the first and second rocker two parallel four joints for height adjustable connection of the side parts to the guide rail arrangement 7.
The guide rail arrangement 7 is formed by two parallel guide rail pairs extending along a vehicle longitudinal direction from which a section of a first guide rail pair is shown in FIG. 1. The upper guide rail 71a is pivotably connected to the rocker 3, while the lower guide rail 71b is connected to the vehicle floor.
The rockers are part of a height adjustment mechanism together with a manual drive unit or an electromotive drive unit 8 which allows for raising or lowering the seat part 1 relative to the guide rail arrangement 7 or vehicle floor, respectively, by pivoting the rockers. The drive unit 8 comprises a manually driven lever or hand wheel or an electrical motor and a gear with an output pinion, which are connected to the side part 21. The output pinion engages in a toothing of a tooth segment connected to the cross tube 4 and can be rotated in respect to the tooth segment for adjusting the seat height.
When operating the height adjustment mechanism the first rocker 3 arranged on the first end 41 of the cross tube 4 is driven and moved by means of the drive unit 8, whereby the adjustment movement is transferred synchronically to the second rocker connected to a second end of the cross tube 4 via the cross tube 4. In this manner the first and second rockers of the rear rocker pair are pivoted, the seat part 1 is adjusted thereby and the third and fourth rockers of the front rocker pair are moved passively. Thus, the rear and front rocker pairs can be pivoted for this purpose along a pivot direction parallel to each other in order to raise or lower the seat part 1 relative to the guide rail arrangement 7 by pivoting the rear and front rocker pairs.
To leave sufficient space between the side part 21 and the first rocker 3 for mounting the drive unit 8 to the side part 21 and to ensure a play-free connection of the first rocker 3 and the side part 21, a plastic spacer 9 is arranged on the first end 41 of the cross tube 4 between the side part 21 and the first rocker 3. For optical and design reasons it is required that the visible elements of the seat part 1, in particular the guide rail arrangement 7 and the rockers have to be coated. However, since the coating of the visible parts has to be done after the assembly of the height adjustment mechanism by a supplier of the seat part 1 the complete seat part 1 including a side part and the cross tube 4 are also coated which causes additional costs.
Moreover, coating of the above identified part requires a need for a non-conductive bushing whereas no coating allows for the potential to just use grease without bushings or a conductive bushing.